These Definitions are taken
direct from the Microsoft White pages at Technet. Its been shortened
to only include the information for the entries in the Cablenut
adjuster. Enjoy !

1.
DefaultReceiveWindow - The number of receive bytes that AFD
buffers on a connection before imposing flow control. For some
applications, a larger value here gives slightly better performance
at the expense of increased resource utilization.

Value Type:
REG_DWORD

Default: 4096/8192/8192

2.
DefaultSendWindow - This is similar to DefaultReceiveWindow,
but for the send side of connections.

Value Type: REG_DWORD

Default: 4096/8192/8192

3. DisableAddressSharing
- This parameter is used to prevent address sharing (SO_REUSEADDR)
between processes so that if a process opens a socket, no other
process can steal data from it.

Value Type: REG_DWORD

Default: 0

Range: 0, 1

4.
InitialLargeBufferCount - The count of large buffers allocated
by AFD at system startup. Allocate more buffers to improve
performance at the cost of physical memory.

Value Type:
REG_DWORD

Default: 0/2/10

5.
InitialMediumBufferCount - Initial count of medium
buffers.

Value Type: REG_DWORD

Default: 4/8/24

6.
InitialSmallBufferCount - Initial count of small
buffers.

Value Type: REG_DWORD

Default: 8/16/32

7.
LargeBufferSize - The size, in bytes, of large buffers used by
AFD. Smaller values use less memory and larger values can improve
performance.

Value Type: REG_DWORD

Default: PAGE_SIZE
(4096 bytes on i386, 8192 bytes on Alpha)

8.
MaxFastTransmit - This parameter controls the maximum amount
of data that is transferred in a TransmitFile request on the fast
path. Fast I/O is essentially copying data and bypassing the I/O
subsystem, instead of mapping memory and going through the I/O
subsystem. This is advantageous for small amounts of data.

Value
Type: REG_DWORD

Valid Range: 0–0xffffffff

Default:
64 KB

9. MediumBufferSize - The size in bytes of
medium buffers used by AFD.

Value Type: REG_DWORD

Default:
1504

10. PriorityBoost - The priority boost that
AFD gives to a thread when it completes I/O for that thread. If a
multithreaded application experiences starvation of some threads, the
problem may be remedied by reducing this value.

Value Type:
REG_DWORD

Default: 2

Valid Range: 0–16

11.
SmallBufferSize - The size in bytes of small buffers used by
AFD.

Value Type: REG_DWORD

Default: 128

12.
TransmitWorker - This parameter controls how Afd.sys uses
system threads. Setting it to 0x10 causes AFD to use system threads
to perform IO that results from a long (more than 2 SendPacketLength
worth of data) TransmitFile request. Setting it to 0x20 causes AFD to
use kernel-mode APC for IO and to execute everything in the context
of the same thread. This is new in Windows 2000 and can improve
performance by reducing the number of context switches in long
TransmitFile requests.

Value Type: REG_DWORD

Default:
0x10

Valid Range: 0x10, 0x20

13.
FastSendDatagramThreshold - Datagrams smaller than the value
of this parameter go through the fast I/O path or are buffered on
send. Larger ones are held until the datagram is actually sent. The
default value was found by testing to be the best overall value for
performance. Fast I/O means copying data and bypassing the I/O
subsystem, instead of mapping memory and going through the I/O
subsystem. This is advantageous for small amounts of data.

Value
Type: REG_DWORD

Default: 1024

14.
EnableFastRouteLookup - Fast route look-up is enabled if this
flag is set. This can make route lookups faster at the expense of
non-paged pool memory. This parameter is created by the Routing and
Remote Access Service.

Value Type: REG_DWORD—Boolean

Valid Range: 0, 1 (false, true)

Default: 0 (false)

15. EnablePMTUDiscovery - Setting this parameter
to 1 (True) causes TCP to attempt to discover the Maximum
Transmission Unit (MTU or largest packet size) over the path to a
remote machine. By discovering the Path MTU and limiting TCP segments
to this size, TCP can eliminate fragmentation at routers along the
path which connect networks with different MTUs. Fragmentation
adversely affects TCP throughput and network congestion.

Value
Type: REG_DWORD—Boolean

Valid Range: 0, 1 (false, true)

Default: 1 (true)

16. IgnorePushBitOnReceives
- Normally, Windows 2000 completes a Windows Sockets Receive when one
of the following occurs:

* Data arrives with the push bit
set.

* The user recv buffer is full.

* 0.5 seconds
have elapsed since any data arrived.

Setting this parameter to
a 1 causes Afd.sys to treat all incoming packets as though the push
bit was set. This should only be done when necessary to work
around client TCP/IP implementations that are not properly pushing
data.

Value Type: REG_DWORD—Boolean

Valid Range:
0, 1 (false, true)

Default: 0 (false)

17.
GlobalMaxTcpWindowSize - The TcpWindowSize parameter can be
used to set the receive window on a per-interface basis. This
parameter can be used to set a global limit for the TCP window size
on a system-wide basis.

Value Type: REG_DWORD—Number of
bytes

Valid Range: 0–0x3FFFFFFF

Default: This
parameter does not exist by default.

18. MaxFreeTcbs
- This parameter controls the number of cached (pre-allocated)
Transport Control Blocks (TCBs) that are available. A Transport
Control Block is a data structure that is maintained for each TCP
connection.

Value Type: REG_DWORD—number

Valid
Range: 0–0xFFFFFFFF

Default: The following default
values are used (note that small is defined as a computer with less
than19 MB of RAM, medium is 19–63 MB of RAM, and large is 64 MB
or more of RAM. Although this code still exists, nearly all computers
are large now).

Windows 2000 Professional:

* Small
system—250 * Medium system—500 * Large
system—1000

19. MaxHashTableSize -
This value should be set to a power of 2 (for example, 512, 1024,
2048, and so on.) If this value is not a power of 2, the system
configures the hash table to the next power of 2 value (for example,
a setting of 513 is rounded up to 1024.) This value controls how fast
the system can find a TCP control block and should be increased if
MaxFreeTcbs is increased from the default.

Value Type:
REG_DWORD—number (must be a power of 2)

Valid Range:
0x40–0x10000 (64-65536 decimal)

Default: 512

20.
MaxNormLookupMemory - This parameter controls the maximum
amount of memory that the system allows for the route table data and
the routes themselves. It is designed to prevent memory exhaustion on
the computer caused by adding large numbers of routes.

Value
Type: REG_DWORD—number

Valid Range: Any DWORD
(0xFFFFFFFF means no limit on memory.)

For Windows 2000
Professional:

150,000 bytes, which accommodates 1000
routes.

21. SackOpts - This parameter controls
whether or not Selective Acknowledgment (SACK, specified in RFC 2018)
support is enabled.

Value Type: REG_DWORD—Boolean

Valid Range: 0, 1 (false, true)

Default: 1 (true)

22. SynAttackProtect - Synattack protection
involves reducing the amount of retransmissions for the SYN-ACKS,
which will reduce the time for which resources have to remain
allocated. The allocation of route cache entry resources is delayed
until a connection is made. If synattackprotect = 2, then the
connection indication to AFD is delayed until the three-way handshake
is completed. Note that the actions taken by the protection mechanism
only occur if TcpMaxHalfOpen and TcpMaxHalfOpenRetried settings are
exceeded.

23. Tcp1323Opts - This
parameter controls RFC 1323 time stamps and window-scaling options.
Time stamps and window scaling are enabled by default, but can be
manipulated with flag bits. Bit 0 controls window scaling, and bit 1
controls time stamps.

25. TcpMaxDupAcks - This
parameter determines the number of duplicate ACKs that must be
received for the same sequence number of sent data before fast
retransmit is triggered to resend the segment that has been dropped
in transit.

Value Type: REG_DWORD—number

Valid
Range: 1–3

Default: 2

26. TcpMaxHalfOpen
- This parameter controls the number of connections in the SYN-RCVD
state allowed before SYN-ATTACK protection begins to operate.

Value
Type: REG_DWORD—number

Valid Range: 100–0xFFFF

Default: 100 (Professional)

27.
TcpMaxHalfOpenRetried - This parameter controls the number of
connections in the SYN-RCVD state for which there has been at least
one retransmission of the SYN sent, before SYN-ATTACK attack
protection begins to operate.

Value Type: REG_DWORD—number

Valid Range: 80–0xFFFF

Default: 80
(Professional)

28. TcpRecvSegmentSize - Specifies
the maximum receive segment size.

Value Type:
REG_DWORD

Default: 1460

29.
TcpSendSegmentSize - Specifies the maximum send segment size.

Value
Type: REG_DWORD

Default: 1460

30. TcpTimedWaitDelay
- Determines the time that must elapse before TCP can release a
closed connection and reuse its resources.

32. TcpWindowSize - This parameter determines the
maximum TCP receive window size offered by the system. The receive
window specifies the number of bytes a sender may transmit without
receiving an acknowledgment. In general, larger receive windows will
improve performance over high (delay * bandwidth ) networks. For
highest efficiency, the receive window should be an even multiple of
the TCP Maximum Segment Size (MSS).

Value Type:
REG_DWORD—number of bytes

Valid Range: 0–0x3FFFFFFF

33. MaxConnectionsPer1_0Server &
MaxConnectionsPerServer - HTTP specification requires that no one
computer can have more than 2 simultaneous connections to any single
HTTP server. This will affect all Windows application that uses the
standard API, including Internet Explorer. People who keep multiple
files on an online hard drive hate this restriction, because they can
only download two or four files at a time. Windows developers choose
to limit the maximum connections to a HTTP 1.0 server to four. In the
HTTP 1.1 specification the number of connections was mandated to
2.

Value Type: REG_DWORD

Default: 4, 2

34.
DefaultTTL - Specifies the default Time To Live (TTL) value
set in the header of outgoing IP packets. The TTL determines the
maximum amount of time an IP packet may live in the network without
reaching its destination.

Value Type: REG_DWORD—Number
of seconds/hops

Valid Range: 0–0xff (0–255
decimal)

Default: 128

35. DisableUserTOSSetting
- This parameter can be used to allow programs to manipulate the Type
Of Service (TOS) bits in the header of outgoing IP packets.

Value
Type: REG_DWORD—Boolean

Valid Range: 0, 1 (false, true)

Default: 1 (true)

36. TcpMaxDataRetransmissions
- This parameter controls the number of times that TCP retransmits an
individual data segment (not connection request segments) before
aborting the connection.

Value Type: REG_DWORD—number

Valid Range: 0–0xFFFFFFFF

Default: 5

37.
DefaultTOSvalue - The IP header in every datagram specifies a
Type of Service (ToS) value that can be used to specify the quality
of service (QoS) setting for IP datagrams. The ToS value indicates
the military origin of the protocol because it was designed for the
Advanced Research Project Agency Networks that was the predecessor to
the current Internet.